Boring bar



April 30, 194.6 A. voNADA BORING BAR Filed June 8, 1944 FIGS- INVENTOR. PHILLIP A..VONA DA Patented Apr. 30, 1946 warren STATES PATENT OFFICE BORING BAR Phillip A. Vonada, Dayton, Ohio Application June 8, 1944, Serial No. 539,369

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370' 0. G; 757) 3 Claims.

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the-payment to me of any royalty thereon.

The present invention relates to cutting bar holders for metal working machines.

Both in boring and turning; as well as in other similar types of metal cutting machines, there is difficulty, especially in the-heavy duty class of machine, in providing a sufiiciently firm or solid foundation or base as a tool holder. A further difficulty is in adequately supporting the cutting end of the tool when cutting on relatively large diameters. In boring, for instance, the holder for the cuttingbar is disposed at the approximate center of 'the circle of the cut and the cutter bar terminating in the cutter bladeextends in a generally radial. direction from the holder to the surface being cut. On small diameter work the length of bar, from holder to cut, is relatively short, with corresponding small leverage. As the diameter increases, the length of bar increases and the leverage is'increased in proportion. As the leverage increases,the yield of the bar, under stress of the cut, tends to produce irregularities, inaccuracies or imperfections in the work. This is serious enough in therough cuts but in the final cuts is not permissible. Accordingly, there are definiterecognized limits to the length of cutting bar between its support and the surface being cut. Of course, the resistance of the barmay be increased by increasing its width and thickness dimensions relative to its length, but there are definite recognized limits beyond which that policy is not practicable.

The present invention meetsand overcomes. the above and other objections and provides a simple, efficient and compact cutting tool holder adequatelybracing the cutter bar for a wide range ofdiametersof cuts.

In order to more clearly disclose the construction, operation and use of the invention, reference should be had to the accompanying drawing forming part of the present application. Throughout the diiferent figures of the drawing, like reference characters designatethe same parts in the different views.

In the drawing:

Fig. 1 is a top plan view of the invention;

Fig. 2 is a front elevation of the clamping block, with the machine bed guide indicated;

Fig. 3 is a perspective view of lower half of block of Fig. 1;.

Fig; 4 is a top plan view of a tocl supporting rod;

Fig. 5 is-a front view of a eollet adapted to be mounted in the block of Fig. '2; and

Fig. 6 is aside elevation of Fig. 5.

Referring to the drawing in detail, l indicates the lower and 2 the upper block of the clamp member for securing the tool holding rods- This clamp is provided with cooperating rod seats 3 in its respective upper and lower members adapted to be aligned and when so aligned, to-receiv'e or securely seat therein tool holding or cutting bar supporting rods 4. It is clamped in operative position about rods 4 by a threaded post 5 passed vertically through the approximate center of the assembled blocks and provided with a collar 6 adapted to engage the lower face of the lower block i. By tightening nut 1', the blocks I and! may be clamped tightly together thereby securing the rods 4 in placein seats 3.

As a simple means of quickly and accurately guiding blocks I and 2 to aligned or clamping position, small spring pressed guiding plungers 8 are provided along the approximate longitudinal center line of the lower block I adapted to register with and seat in corresponding sockets 9 in the upper block 2. These plungers, in operative positions, are indicated, in dotted line, inFig. 2. Each is provided with a collar l0 having free movement in an enlarged bore l l communicating with the smaller bore through which the plunger extends to seat in socket 9. The lower end of this larger bore is closed by "a threaded plug or nut I2 between which and collar I0 is confined coil spring I3, continually exerting pressureto yieldingly maintain plungers 8 in operativeguiding positions.

Threaded post 5 extends through the approximate center of theassembled blocks I and 2 and is adapted to be and intended to be mounted on the machine bed in the same approximate position as the regular standard tool holder. As is wellknown, such'holders are provided with suitable means for advancing them toward br from their work, along the bed or way of the respective machine and, when desired, securing them in selected adjusted positions. Usually, in turning or boring operations, to which this invention is applicable. the tool holder is automatically fed, relatively to the work being done. The type of machine, the relative position of the tool holder thereon, the mounting of the tool holder on the machineand various-types of' mechanism for feeding the tool holder are all well known to every one skilled in the art to which this invention relates and, accordingly, need not be either illustratedordescribed here. The guides or way [4 of themasides of that center, laterally spaced tool bar sup-- porting rods 4 may be firmly seated in the block. That, in turn, makes it possible to mount thetool bar. supporting rod 4 at a considerably greater distance radially of the out from the post toward the work than is possible without this invention.

That, alone, would not sufiiciently counteract the increased leverage, although some of that leverage would be taken up by the supporting bar and clamp.

In order to get the greatest practicable bracing effect against or offsetting the extended cutting bar and enable the cutting end of the bar to be projected or extended radially from post'5 to take full advantage of this invention, two parallel rods 4 are used, both securelyclamped between blocks 1 and 2. Each of these rods is provided with a bore or passage l5 'extendingcentrally through it, diagonally at an angle of about 45 to its lateral cross section and a short distance from one end. The bores here shown are to receive tool bars of approximate square cross section and, therefore, are of like cross section. For tool bars of different cros section, the bore [5 would be of correspondingly diiferent shape. To securely lock the tool bar in its supporting rod 4 suitable set screws or the like are used, the respective rod end-being cut of! diagonally or: in a plane parallel with and slightly spaced therefrom to provide a-plane surface for the binding screws. In use, the rods 4 are seated in the clamp between blocks and 2 with their'respective bores l5 aligned, as shown in Fig. 1. Then the tool bar 16 is seated in both aligned bores of the rods 4, moved to the desired position to make the required cut and positively locked in that position by the set screws. Then the nut is tightened on 5 solidly clamping rods 4 in place, with their tool bar [6. The guide plate ll, of post 5, as will be well understood, plays freely in the way [4 of the machine for usual adjustments, being secured in any such adjusted position by the bolts l4. The two parallelrods 4 provide a wide-base, firm, bracin support for tool bar I 6 completely oflsetting most of the leverage otherwise imposed upon it for a considerable range of diameters beyond what would be the maximum where the tool bar is supported by a post having the approximate position of post 5.

In combination with the clamping block, where smaller .tool holders and cutting tools are to be used, a collettype adapted (Figs. 5 and 6) is provided. The collet type holder here shown comprises a split tube I8 having a friction grip hold or clutch action and having an external over-all diameter very slightly greater than the over-all internal diameter of the bores formed between the blocks l and 2 when assembled in operative position. The free end is headed as at l9 and knurled to provide easy handling and positioning and to act as a stop when placing in the clamp. With such a collet holder in position, tightening of the nut on post 5 will compress l8 sufiiciently to grip tightly the rod 4 seated in the tube.

A very important and novel feature of this bore whichreceives rod 4. That bore is not concentric with the longitudinal axis but eccentric. The degree of eccentricity is variable and may be greater in one than in another. Likewise bores 20 may be of different diameters. It will be obvious that, assuming two such collet type holders clamped in position in the same way that rods 4 have been described as clamped and each carrying a rod 4 clamped therein, the rods being so placed that bores l5 thereof are aligned, a cutting tool bar 16 may be seated in and supported by those rods in the same way as hereinabove disclosed. A much smaller cutting bar, with correspondingly smaller supporting rods may be used by this assembly.

The eccentric position of bores 20 provides for a considerable range of adjustments of the supporting rods 4. Each collet holder may be rotated to carry its bore 20 and the corresponding rod 4 to any one of a wide range of positions around or eccentric to the longitudinal center or axis of the collet. The pair of collets thus adjusted provide corresponding adjustment of the cutting tool relatively to the work. 7

It will be well understood that a single collet type holder, with rod 4 and tool bar may be used, if desired under proper conditions. In that case. the eccentric bore of the collet gives a considerable range of adjustments of the cutter bar impossible in other holdersi. e. adjustments around and relative to the longitudinal axis of the collet or of the corresponding bore between blocks I and 2. r

Although the bores I5 have been shown as diagonal and disposed at an angle of about 45", it will be understood that the invention is not in any degree limited to such angular disposition. That is a preferred arrangement. The bore [5 may be disposed radially of bars 4 or at angles between the radius and the 45 angle, according to the work to be done and other well known controlling factors.

It is thought that the construction, operation and use of the invention will be clear from the preceding detailed description.

Many changes may be made in the construction, arrangement and disposition of the several parts of the invention within the scope of the appended claims without departing from the field of the invention and it is meant to include all such within this application wherein only one preferred construction and arrangement and one -modification thereof have been disclosed purely by way of illustration and with no thought or intent of limiting the claims thereby, and it is ment to include all such within this application.

Having thus described my invention what I claim and desire to protect by Letters Patent is:

1. In combination, a pair of clamping blocks provided with spaced parallel rod-receiving seats, the seats of one block being adapted to be aligned with those of the other one of said blocks bein provided with guide pin sockets in its inner face while the other is provided with bores of corresponding diameter alignable therewith and bores of greater diameter concentric with the first bores said bores together extending completely through the respective block. plungers freely movable in said bores and, in operative position, extending into said sockets, said plunger carrying heads of increased diameter movable in'the bores of greater diameter, threaded plug closures for said larger diameter bores, compression coil springs confined between said plug and said head, means disposed centrally of the aforesaid blocks approximately midway between the seats thereof for securing said blocks to the guide-way of a metal working machine, rods mounted in the aforesaid seats and provided with aligned cutter bar openings therethrough disposed at an angle to the width of said rods and means for clamping the aforesaid blocks in rod securing position.

2. In combination, a lower clamping block provided with parallel spaced rod-receiving seats and centrally disposed yielding guide plungers, an upper cooperating block having cooperating complementary rod-receiving seats adapted to be guided to operative position by said plungers, a pair of cutter bar receiving rods disposed in said seats between said blocks, and provided with aligned cutter bar receiving openings therethrough disposed at an angle to the width of the PHILLIP A. VONADA. 

